The present invention pertains to an instrument for protecting the posterior capsule of the lens during cataract surgery by a small wound incision technique, commonly known as phaco-emulsification.
In recent years, two surgical techniques for removing a cataract from the eye are employed, the large wound incision technique, and the small would incision technique also referred to as phaco-emulsification. Intra-ocular lens implants are used with both techniques. In the large wound incision technique, a large incision almost half the circumference of the cornea is made, and the cataract is expressed or squeezed out of the eye manually. The main advantage of this technique over phaco-emulsification is that it is easier to perform. The disadvantages are that it takes a much longer time to recuperate due to the large wound, and also creates more astigmatism.
The small wound incision technique, illustrated in FIGS. 1 and 2, employs an ultra-sonic aspirating needle 10 which cuts the cataract 12 into tiny pieces and aspirates them out of the eye. This is accomplished through a small opening 14 on the eye wall. The advantages are that the eye recuperates faster, the patient returns to work sooner, and less astigmatism results. The disadvantages are that it is a more difficult technique, and requires expensive instruments.
The main cause of difficulty with this technique is the problem of breaking the lens posterior capsule 16. An intact, unbroken posterior capsule is important for the well-being of the eye after the operation. During surgery, only the substance of the cataract is removed, and the posterior capsule (the back cellophane-like envelope of the cataract lens) is left intact, and remains inside the eye. It is important to leave the posterior capsule intact for the success of the operation, since vitreous will be released through any break or tear and if this happens good vision may not be achieved, and serious complications will likely result later. An intact posterior capsule is essential for ideal placement of an intra-ocular lens implant.
Since the cataract nucleus and the posterior capsule are located very close to each other, the danger of breaking or damaging the posterior capsule by the powerful ultra-sonic tip is constantly present. A good analogy is the task of cutting a pie directly on top of a table cloth.
It is a difficult task fraught with tension and anxiety.
Accordingly, the object of the present invention is to provide an instrument that is used during surgery for removal of a cataract by phaco-emulsification which will effectively protect the posterior capsule from the powerful ultrasonic cutting tip.